And be renewed. The second part of the rule for a devout and holy life is to live, not in our own spirit, but in the Spirit of Christ. But what is meant by -- the spirit of your mind? I understand it simply to mean, -- Be renewed, not only with respect to the inferior appetites or desires, which are manifestly sinful, but with respect also to that part of the soul which is reckoned most noble and excellent. And here again, he brings forward to view that Queen which philosophers are accustomed almost to adore. There is an implied contrast between the spirit of our mind and the Divine and heavenly Spirit, who produces in us another and a new mind. How much there is in us that is sound or uncorrupted may be easily gathered from this passage, which enjoins us to correct chiefly the reason or mind, in which we are apt to imagine that there is nothing but what is virtuous and deserves commendation.

And be renewed - That is, it is necessary that a man who has been following these should become a new man; see the notes on John 3:3 ff., compare the notes on 2-Corinthians 4:16. The word used here - ἀνανεόω ananeoō - does not occur elsewhere in the New Testament; but it has the same meaning as the word used in 2-Corinthians 4:16, and Colossians 3:10. It means to make new, and is descriptive of the work of regeneration. This was addressed to the church, and to those whom Paul regarded as Christians; and we learn from this:
(1) that it is necessary that man should be "renewed" in order to be saved.
(2) that it is proper to exhort Christians to be renewed. They need renovated strength every day.
(3) that it is a matter of "obligation" to be renewed. People are "bound" thus to be renovated, And,
(4) that they have sufficient natural ability to change from the condition of the old to that of the "new" man, or they could not be exhorted to it.
(See the supplementary Romans 8:7, note; Galatians 5:17, note.)
In the spirit of your mind - In your temper; your heart; your nature.

And be renewed in the spirit of your mind - Their old mode of living was to be abandoned; a new one to be assumed. The mind is to be renovated; and not only its general complexion, but the very spirit of it; all its faculties and powers must be thoroughly, completely, and universally renewed. Plautus uses a similar expression describing deep distress, and answerable to our phrase innermost soul: -
Paupertas, pavor territat mentem animi.
Poverty and dread alarm my innermost soul.
Epid., l. 519.

And be renewed in the (f) spirit of your mind;
(f) Where there ought to have been the greatest force of reason, there is the greatest corruption of all, which gradually weakens all things.

And be renewed in the spirit of your mind. Or by the Spirit that is in your mind; that is, by the Holy Spirit; who is in the saints, and is the author of renovation in them; and who is the reviver and carrier on, and finisher of that work, and therefore that is called the renewing of the Holy Spirit, Titus 3:5 or rather the mind of man, which is a spirit, of a spiritual nature, immaterial and immortal, and is the seat of that renewing work of the Spirit of God; which shows, that the more noble part of man stands in need of renovation, being corrupted by sin: and this renewing in it, designs not the first work of renovation; for these Ephesians had been renewed, and were made new creatures in Christ; but the gradual progress of it; and takes in, if not principally intends, a renewal, or an increase of spiritual light and knowledge, of life and strength, of joy and comfort, and fresh supplies of grace, and a revival of the exercise of grace; and in short, a renewal of spiritual youth, and a restoration of the saints to that state and condition they were in, in times past: and the exhortation to this can only mean, that it becomes saints to be concerned for such revivings and renewings, and to pray for them, as David did, Psalm 51:10 for otherwise, this is as much the work of the Spirit of God, as renovation is at first; and he only who is sent forth, and renews the face of the earth, year by year, can renew us daily in the Spirit of our minds.

be renewed--The Greek (ananeousthai) implies "the continued renewal in the youth of the new man." A different Greek word (anakainousthai) implies "renewal from the old state."
in the spirit of your mind--As there is no Greek for "in," which there is at Ephesians 4:17, "in the vanity of their mind," it is better to translate, "By the Spirit of your mind," that is, by your new spiritual nature; the restored and divinely informed leading principle of the mind. The "spirit" of man in New Testament is only then used in its proper sense, as worthy of its place and governing functions, when it is one spirit with the Lord. The natural, or animal man, is described as "not having the Spirit" (Jde 1:19) [ALFORD]. Spirit is not in this sense attributed to the unregenerate (1-Thessalonians 5:23).

The spirit of your mind - The very ground of your heart.